An antioxidant compound, C₆H₁₈O₂₄P₆, found abundantly in seeds and the bran of grain, that is the principal storage form of phosphorus in plants. Phytic acid is a strong chelator of calcium, zinc, and other minerals, and diets based on foods high in phytic acid, such as unrefined flour, can cause mineral deficiencies unless it is broken down by the sprouting of the seeds or by fermentation. Also called inositol hexakisphosphate.